[e90_enjoyer]

Hi all,

Recently developed a strange metallic rattle that matches the RPM of the engine and goes away pretty much exactly at 4100 RPM. Typical marbles in a can sound. It's quiet enough to be drowned out by my stereo.

If I rev it out a few times it will totally go away for a while, usually until the end of my drive. It pretty much only happens with load on the engine, very rarely does it in neutral.

Car is a 2006 330i, 6MT, sport package, just ticked over 151k. December 05 build date. No mechanical issues of any kind until recently.

I thought it could be DISA related. I had done the big DISA flap maybe 5k miles ago - almost fell apart, but I was able to pull the valve and the pin was still inside the flap. I left the small one alone since it was more work and I didn't have time.

I went ahead and did the smaller DISA, and lo and behold it was fine, albeit covered in oil. Replaced it anyway, and sound is still there.

I'll try and get a video of it while it does it.

Being that it goes away exactly at 4100rpm and goes away for a while - what else could it be? It's tied to RPM but doesn't sound quite like lifter tick, it's more random than a controlled "tick tick tick". Scared to think it could be timing related, or something with the VANOS adjusters. My car is too old to be covered or affected by the recall.

I have zero codes, zero drivability issues besides the sound. In fact after doing both DISAs it's the smoothest it's ever been, cant even tell the car is on when idling. Lots of power. INPA report is clean.

Would love to hear what you guys think, thanks so much !

[avocet]

I just had a similar situation... my car started to tick. I had the lifters replaced under warranty years ago. I was pretty worried since it actually started while in a shop for unrelated work. The guys calls me up and says "hey your engine is ticking..."
I was kinda freaked and wondered if they took her out for a rip and blew a shift. I did have a dash cam that they didn't turn off and saw the test drive they did. Nothing there to suggest it was abuse. Tick became inaudible at higher RPM. Didn't take note of the RPMs.
I took her home and immediately changed the oil. As I was about to shut the engine off a big cloud of white smoke appeared and she started to misfire badly. I was freaking out. It then threw a CEL. Code? Misfire #4 0029D0. Swapped coils and misfire went to the other cylinder.
Long story short, it was a failing coil that caused the tick, and it didn't throw a code while she ticked, and seemed to drive fine. High tension short causing the snap? Who knows. New Dinan coils from ECS(the cheapest brand name I could find) and she runs better than ever.